UI Tweak: Add a convenience button for switching to Bone Constraints Tab

To reduce user confusion, we were already presenting users with an error message
when they tried to edit constraints for bones from the Object Constraints tab.
This commit just makes things more convenient by adding a button which takes
users to the right tab when clicked.

release/scripts/startup/bl_ui/properties_constraint.py

@@ -858,8 +858,9 @@ class OBJECT_PT_constraints(ConstraintButtonsPanel, Panel):
 
         if obj.type == 'ARMATURE' and obj.mode in {'EDIT', 'POSE'}:
             box = layout.box()
-            box.alert = True
-            box.label(icon='INFO', text="See Bone Constraints tab to Add Constraints to active bone")
+            box.alert = True  # XXX: this should apply to the box background
+            box.label(icon='INFO', text="Constraints for active bone do not live here")
+            box.operator("wm.properties_context_change", icon='CONSTRAINT_BONE', text="Go to Bone Constraints tab..").context = 'BONE_CONSTRAINT'
         else:
             layout.operator_menu_enum("object.constraint_add", "type", text="Add Object Constraint")